Sensitive to smaller bugs
The sensor head contains an infrared light-emitting diode matched with a phototransistor. Shuman reversed the collector and emitter to give the device a lower gain, allowing the phototransistor to be biased in the linear region, which makes it more sensitive to small insects. The latest versions use matched pairs from QT Optoelectronics in Sunnyvale, Calif., which seem to be working better than previous matched pairs, he said.
Shuman has made several improvements to the probe since he developed the first prototype five or six years ago. For one, electronic noise is not the problem it used to be, according to Thomas Phillips, associate professor of entomology at Oklahoma State University in Stillwater. He operates one of eight evaluation sites around the country on the current version and says he sees more than 90 percent accuracy.
Upgrading the system to use its sensitivity to distinguish between insect types could prove beneficial, Phillips said. "In the stored-grain ecosystem, if you will, we have a whole range of insects," he said. "Some of them are eating the grain, but some are eating the insects that are eating the grain."